Selective system



mm 2, m4. mums? 4 Pf. NQRTQN ET AL SELECTIVE SYSTEM Filed Dec. 29, 1923 W Wm Patented Dec. 2, 1924.

UNETED STATES PATENT @FFHQE.

PHILANDER NORTON AND DAVID '1. MAY, OF PORT WASHINGTON, NEW YORK, AS-

SIGNORS TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. Y.,

A CORPORATION OF NEW YORK.

SELECTIVE SYSTEM.

Application filed December 29, 1923. Serial No. 683,297.

To all whom it may concern:

Be it known that we, PHILANDER NORTON and DAVID T. MAY, citizens of the United States of America, both residing at Port *Washington, in the county of Nassau and State of New York, have invented certain new and useful Improvements in Selective Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to selective systems, and more particularly to means for causing the selective operation of electro-responsive devices, such as telephone ringers, relays, etc.

The object of the invention is to simplify such systems and improve their operating efficiency. 1

The principal feature of the invention resides in inserting an electric discharge device in series with the device to be selectively operated, said discharge device having the characteristics of preventing the passage of current below a specified voltage, of passing current when the voltage is increased beyond this point and of interrupting the current when the voltage falls below a certain other value.

The invention will be more clearly understood froin the following description and drawings, Fig. 1 of which represents what is known as a four-party selective ringing system embodying the invention and Fig. 2 represents a modification of the invention as applied to miscellaneous electromagnetic devices, such as relays, etc.

In selective ringing telephone systems wherein positive and negative pulsing currents are transmitted over one or the other of the line conductors to selectively actuate one of a plurality of telephone ringers connected between one side of the line and ground, it has heretofore been found desirable to only connect. the ringers to the line when a ringing signal is to be transmitt-ed. In practice this has been effected by bridging a relay in series with a condenser across the two line conductors for each ringer and causing each relay to control the connection of its associated ringer with the proper side of the line when ringing current is applied thereto. Such a system is shown in U. S. @Patent 644,647 to Messrs. Thompson and Robes, dated March 6, 1900. A modification of this system is in use wherein the bridged relays are omitted and each ringer is connected between the line conductors and ground in series with an arrangement consisting of a condenser and a high resistance connected in parallel.

In accordance with the present invention the latter arrangement is modified by replacing the condenser and high resistance in series with each ringer, with a vacuum discharge device of the type such as has been well known for a number of years in lighting which consists of alkaline metal electrodes inclosed with a rare gas in a sealed tube and which has the characteristic of preventing the passage of current avlien the voltage is below a specified given quired to break down the discharge gap.

Referring to the drawings C (Fig. 1) represents a telephone. switchboard cord circuit arranged for four-party selective ringing, that is, keys K, K, K and K are arranged when operated to apply either negative or positive pulsating current to either one side or the other of the line L. R R R and R are biased telephone ringers of a well known type, R being biased to respond to positive pulsating current flowing in the line conductor L B being biased to respond to negative pulsating current in the line conductor L and R and R being biased to respond to positive. and negative pulsating current respectively in the line conductor L Ringers R, R R and R are each connected between one side of the line L and ground in series with electrical discharge devices 1, 2, 3 and 4, respectively. The operation is as follows: Let it be assumed that plug P has been inserted in jack J and that key K has been operated to connect tit) kaline metal, relatively closely spaced with respect to each other.

3. In a telephone signaling system, in combination, a line, means for transmitting intermittent current of definite direction over one conductor of said line, an earth branch including a polarized bell connected with said conductor, said polarized bell having its armature biased to move in one direction with each current impulse and in an opposite direction with each interruption of said current, and an electric discharge device in series with said bell in said branch.

4. The combination, in a telephone signaling system, of a metallic line circuit, a source of intermittent current of "definite direction connected to one of the-conductors thereof,

a subscribers signaling apparatus comprising a polarized bell connected in a branch circuit between said conductor and ground, said bell being biased to vibrate in response to said definite direction current, and an electric discharge device, comprising a'sealed receptacle containing an alkaline metal electrode and a rare gas, in serieswith said polarized bell in said branch circuit.

5. In a telephone signaling system, the combination with one conductor of a metallic line circuit, of means for transmitting an intermittent current of definite direction over said conductor, of an earth branch of said conductor serially including a polarized ringer biased to respond to said intermittent current of definite direction, and an electric discharge device com rising a sealed receptacle'enclosing an al aline metal electrode and a rare gas.

6. In a selective signaling system, line conductors, a plurality of biased signaling devices connected thereto, a signahng current generator adapted to transmit an intermittent current of definite direction over one of said line conductors, and an electric discharge device comprising a sealed receptacle containing an alkaline metal electrode and a rare gas in series with each of said signaling devices.

In a selective signaling system, a metallic line circuit, a plurality of biased ringers connected thereto, a source of signaling current for transmitting an intermittent current of definite direction, an electric discharge device comprisin a sealed receptacle, containing an alkaline metal electrode and a rare gas, in series with each of said ringers, and switching means for connecting said source to one of said conductors.

8. In a selective signaling system, a metallic circuit telephone line terminating in a central office, a plurality of subscribers stations connected thereto, a biased ringer individual to each subscribers station, two of said ringers being connected to each line conductor, the two ringers which are connected to the same conductor being oppositely biased, a signaling current generator for transmitting either positive or negative pulsating 'current, switching means for connecting either said ositive or negative current to either. of said line conductors, and an electric discharge device com rising a sealed receptacle containing an alka ine metal electrode and a rare gas in series with each of said biased ringers. Y

9. In a telephone signaling system, the combination with one conductor of a metallic line circuit, of means for transmit. ting an intermittent current of definite direction over said conductor, and an earth branch of said conductor serially includin a polarized ringer biased to respond to said intermittent current and an electric discharge device comprising an evacuated:

vessel containing twoelectrodes relatively closely opposed.

10. In a selective signaling system, a metallic line circuit, a plurality of biased ringers connected thereto, a source of signaling current for transmitting either positive or negative pulsating current, an electric discharge device, comprising an evacuated vessel containing two relatively closely opposed electrodes, in series with each of said ringers, and switching means for connccting said source to one of said conductors.

11. In a selective system, a line, a device to be selectively operated connected thereto, a plurality of sources of current of difierent voltage, switching means for applying said different voltages to said line, and a discharge tube in series with said device, so

constructed and arranged that it will maintain the energizing circuit of said device open during application to the line of certain of said voltages below a certain value, and will close said circuit upon the connection to said line of a source of voltage above said certain value. i

12. In a selective system, a line, a device to be selectively operated connected thereto, a lurality of sources of current of diiferent v0 tage, switching means for applying said difi'erent voltages to said line, a discharge tube in series with said device comprising a sealed receptacle containin a pair of electrodes and a rare gas, sai device being so constructed and arranged that it will maintain the energizing circuit of said device open during application to the line otcertain of said voltages below a certain value,

and will close said circuit upon the connecranged as to prevent current applied to the line from energizing said marginal device when a voltage of said current is less than a certain value, to pass current to energize 5 said device when the voltage of the current applied is above said certain Value and to interrupt said current flow when the voltage of the current present in the line is reduced below a certain other value.

In witness whereof, We hereunto subscribe W our names this 22d day of December, A. D.

PHILANDER NORTUN. DAVID 'll. MAY. 

